1. Technical Field
The present invention relates to a sheet manufacturing apparatus and a sheet manufacturing method.
2. Related Art
In the related art, in a sheet manufacturing apparatus, a so-called wet type method of feeding a raw material including fibers into water, disintegrating the material mainly by a mechanical operation, and repulping, is employed. A sheet which is manufactured by the wet type sheet manufacturing method, has a structure in which cellulose fibers which are derived from wood or the like are intertwined with each other, and are partially bonded by a bonding force, such as hydrogen bonding.
In addition, as a manufacturing method of a waste paper sheet or a fiber board which uses paper-manufacturing waste, such as pulp waste, screening waste, or cleaner waste, which is generated when waste paper sheets or the like are disintegrated, as a raw material (pulp raw material), for example, JP-A-10-121400 discloses a method of forming into a predetermined shape by heating and pressing a raw material mixture which is made up to contain 2% by weight to 20% by weight of plastic on a dry weight basis and 10% by weight to 30% by weight of a dry type defibrated raw material (fibrous material), which is made by making a paper sheet or a wood material have a fibrous form by a dry method, on a dry weight basis, by using at least one of types of paper sheets, such as waste paper sheets and the paper-manufacturing waste as a main component.
According to this method, when the raw material of the fiber board has a plastic content at a proportion in which a proportion of plastic in the raw material mixture exceeds a predetermined range, the proportion of plastic in the raw material mixture is brought within the predetermined range by removing a part of plastic in the raw material of the fiber board. In addition, when the raw material of the fiber board has a plastic content at a proportion in which the proportion of plastic in the raw material mixture is below the predetermined range, additional plastic is added so that the proportion of plastic in the raw material mixture is within the predetermined range.
However, in JP-A-10-121400, there is no specific description allowing understanding of how much plastic is contained in the raw material of the fiber board. For this reason, even those skilled in the art cannot realize adjustment of the proportion of plastic to a predetermined proportion. For this reason, the proportion of plastic in this method is inevitably in a wide range of 2% by weight to 20% by weight, and when the proportion of plastic is in such a wide range, strength of the manufactured sheet is not constant, and for example, there is a possibility that a sheet which has extremely insufficient strength may be manufactured.
In addition, a manufacturing method of a desired sheet by recycling waste paper sheets plural times has not been suggested until now.